Spar varnish, urethane, clear coat questions

[Aaron Coffee]

Bit the bullet and ordered epoxy today, went with Raka. Just trying to get things figured out what I need, etc. Found Cabots Spar Varnish at Lowes for $35 a gallon, also had Cabot's spar urethane(didn't look at price). What is the difference and which is preferrable? As far as automotive clear coat, what is the longevity before it needs to be reapplied? And does it require wet sanding(or does it not orange peel)? What order is everything done in, cut profile, stain, epoxy, varnish, then assemble or varnish(or clear coat) after assembly.

Thanks
Aaron

[retnavycpo]

I need to do some refinishing on my teardrop too. The top and back hatch are really dried out. Need to know the best way to remove the old, and apply the new?

Am worried about sanding, thinking it will remove too much wood. Is chemical stripping a viable option?

Pete

[Juneaudave]

Bit the bullet and ordered epoxy today, went with Raka. Just trying to get things figured out what I need, etc. Found Cabots Spar Varnish at Lowes for $35 a gallon, also had Cabot's spar urethane(didn't look at price). What is the difference and which is preferrable? As far as automotive clear coat, what is the longevity before it needs to be reapplied? And does it require wet sanding(or does it not orange peel)? What order is everything done in, cut profile, stain, epoxy, varnish, then assemble or varnish(or clear coat) after assembly.

Thanks
Aaron

Everyone does it different depending on how they are bulding, but you have it right...cut profile (sand) stain (sand) epoxy (sand) and varnish. Somewhere in there...you have to assemble, and generally, you want to apply your varnish or clear coat after everything is together.

I like spar varnish over spar poly for UV protection, but I think you can maybe do better with spar poly if your going to spray with a HPLV set up. I used auto clear on my build for no other reason than I want to learn how to spray paint with HPLV. I can't comment on durability, but I don't see why auto clear wouldn't go for many years with a fresh coat of wax every so often. On the clear, I wet sanded at 1500 grit, then buffed it out with rubbing compound then swirl remover, and finally glaze. Shines like a mirror, but doesn't have "amber" tone you get with a spar varnish...it's truelly clear...hope that helps!!!

[wannabefree]

Hi there. I have a longstanding dislike for poly, but other people seem to think it's great stuff. I have not seen any that holds up well in exterior applications, but haven't looked because, as I said, I hate the stuff. My experience is 30 years old, but burned once I will not be burned again. The problems I see are 2: poor adhesion on oil based stains or oily woods and it looks like plastic on top of wood. My opinion. Others will (venemently) disagree.

I'm not too fond of varnish, either for these reasons: drying time is too long, it crinkles if you put it on too thick, and it's too yellow for me. That said, I used it on the interior of our tear. It has some advantages: it's forgiving, brushable, and so well-suited to amateurs (I am one of those).

I would not recommend Minwax Helmsman. Maybe I got a bad batch, but I ended up throwing out nearly 2 gallons. It would never set up. Cabot is much better. Neither is a really good exterior finish, though. For exterior get a real marine varnish like Epifanes. Read the article in FWW from a couple months back. They tested 6 finishes and though some will argue it was a biased test you can still learn from it.

I am using Emtek9300 from Target Coatings for the exterior. I brushed the top but will spray the sides in a couple days. If brushing use the retarder and thin a bit with water. It goes on beautifully and I laid on 8 coats in 3 hours. Can't do that with varnish. Life is too short to wait for 6-8 coats of varnish to dry!!

As for clearcoat, it is a 2-part finish so should have a long shelf life until you mix it. Then you have about an hour working time. Unless you have used it on small pieces, or something you don't care about (like your car?) I would stay away from it. Life on the wood is another thing. Wood expands and shrinks more than steel and automotive finishes, while flexible, aren't made for wood. That said there are those on this site who swear by it. Here in AZ a lot of cars get clearcoat dandruff. The stuff flakes and peels away after a few years. This happens mostly with dark bottom coats.

I did a lot of research before I turned to Emtek. What finally sold me was the help available on their site. Still, I really don't know for sure how it will behave in the long run and may end up sanding it all off in a couple years. So if you can wait that long, I'll post my results!

Gads, another mile long post. Sorry.

[kennyrayandersen]

Hi there. I have a longstanding dislike for poly, but other people seem to think it's great stuff. I have not seen any that holds up well in exterior applications, but haven't looked because, as I said, I hate the stuff. My experience is 30 years old, but burned once I will not be burned again. The problems I see are 2: poor adhesion on oil based stains or oily woods and it looks like plastic on top of wood. My opinion. Others will (venemently) disagree.

I wouldn’t vehemently disagree – I had a little girl trouble in the past, but I didn’t swear off of ‘em I’ve just never had any trouble with the polyurethanes, but read on.

As for clearcoat, it is a 2-part finish so should have a long shelf life until you mix it. Then you have about an hour working time. Unless you have used it on small pieces, or something you don't care about (like your car?) I would stay away from it. Life on the wood is another thing. Wood expands and shrinks more than steel and automotive finishes, while flexible, isn’t made for wood. That said there are those on this site who swear by it. Here in AZ a lot of cars get clearcoat dandruff. The stuff flakes and peels away after a few years. This happens mostly with dark bottom coats.

I think I used either this or a similar 2-part product in a college wood finishing class. Although I haven’t had the problems that wannabefree has had with the poly, I did have extraordinary results with this type of two-part, I think they called it a plasticine or something like that (I’m not sure of the general category). It produced quite possibly the best finish of any of the ones we used in class including lacquer, varnish, and polyurethane. If I remember right, you had to be a bit careful as if it set up while in the pot, you basically threw the pot away. Also, I don’t remember how it was to clean up, but no worse than some others. I remember it being expensive though, and the instructor told us it only had a self life of 6 months (maybe things have gotten better in 25 years since) and he stored it in the refrigerator to extend the shelf life. I suspect though that this might a really great finish, but for the afore mentioned reasons (cost, shelf life, etc.) I haven’t used it since college. For something like a tear, that is so labor intensive, the initial cost is relatively unimportant (as anybody that had to redo from using an inferior product can testify!). In that case something like this might well be worth the cost and complexity. Do keep us posted. It may not take that long if it turns out there IS a problem.

[wannabefree]

FWIW: I shot 6 coats of Emtek9300 on my tear in 3 hours, not including prep time. It went on easily using a turbine HVLP gun. I would recommend it, but I still consider it unproven as far as weather resistance goes. I'll let you know how it works in 2 years. One thing I am sure of - it's better than any varnish you can get in a box store.

[VermonTear]

So... It's a couple of years later.

How's that Emtek9300 workin on your tear? UV protection work out okay?

ken

[suckerpunched]

maybe I'm a minimulistic......(spelling?) but I used CPES on every inch and three coats or more of spar urethane on the exterior....stored inside during the winter so am hoping this holds for a few years,,,,if not,,,will sand down and refinish